Normally, light generated by table lamps, for example LED table lamps, is symmetrically distributed. However, it is desirable for target objects or areas which require lighting to be located at one side of the table lamp, so that the table lamp can be situated to the side of the table, out of the way of the working area.
Light output by the table lamp to the other side is then wasted, reducing the efficient usage of light. In addition, when table lamps are put on a level desk and turned on, the brightest spot is right under the lamp. To make use of the brightest spot to illuminate an object, a user must move the table lamp closer or tilt the lamp, which for example makes reading uncomfortable or produces glare. There may also be a tendency to bend over a desk in order to move closer to the brightest area, which may be harmful to the eyesight of the user because of the short focus distance.
It has been proposed to provide a table lamp with an asymmetrical light output, for example in GB 2 005 995.
However, providing an asymmetrical output gives rise to limitations to the adjustment of the light output direction. For example, it may require the lamp to be in a fixed position relative to a table, which may be inconvenient for the user, depending on the work they are carrying out, and/or depending on their preference for the position of the table lamp. This preference may for example depend on whether the user is left-handed or right-handed. Users often put table lamps at the front-left or front-right of the table according to their handedness. A right-handed user typically puts the table lamp on the front-left (or back-left) of a desk in order not to block light and therefore cast a shadow on the work piece with their right hand. Similarly, a left-handed user typically puts the table lamp on the front-right (or back-right) of the desk.
A table lamp with asymmetrical light output will not therefore be optimised for positioning in different alternative places. This invention aims to address this problem.